Objective <p>To evaluate the value of magnetic resonance imaging (MRI) in identifying the pathologic complete response (pCR) of patients with locally advanced rectal cancer (LARC) after neoadjuvant therapy (NAT).</p> Materials and methods <p>This retrospective study included 152 patients with LARC who underwent NAT followed by total mesorectal excision (TME) at our hospital between January 2019 and November 2024. The response to NAT was assessed using MRI. At first, the response was assessed according to MRI-based tumor regression grade (mrTRG), which was only on the basis of T2 weighted imaging (T2WI). Then, diffusion weighted imaging (DWI) was added to construct biparametric MRI-based tumor regression grade (BPmrTRG), followed by multiparametric MRI-based tumor regression grade (MPmrTRG) consisting of T2WI, DWI and contrast-enhanced T1-weighted imaging (CE-T1WI). The diagnostic efficacy of the three methods for identifying pCR was assessed by calculating the area under the receiver operating characteristic (ROC) curve (AUC), positive predictive value (PPV), negative predictive value (NPV), sensitivity, and specificity. The DeLong test was used to compare the AUCs of different methods.</p> Results <p>Of the 152 patients, 27 (17.8%) were obtained pCR at surgical histopathological analysis. Among the three different MRI-based TRG methods, MPmrTRG archived the highest AUC of 0.891 (95% CI: 0.814–0.957) to identify pCR after NAT, followed by an AUC of 0.840 (95%CI: 0.745–0.916) for BPmrTRG and 0.729 (95% CI: 0.630–0.818) for mrTRG. Paired comparisons showed that AUC of MPmrTRG was higher than that of mrTRG with statistically significant after Bonferroni correction (<i>p</i> = 0.007), as well as the sensitivity (0.815 vs. 0.481, <i>p</i> = 0.008).</p> Conclusion <p>After adding DWI and CE-T1WI, the multiparametric MRI approach could improve diagnosis performance for identifying pCR after NAT in patients with LARC, which could facility clinicians’ decision and patients’ consultation for the watch and wait strategy to forgo the surgery and preserve the organ.</p>

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Multiparametric MRI approach identifies pathologic complete response in patients with local advanced rectal cancer after neoadjuvant therapy

  • Yudie Pan,
  • Shuxing Wang,
  • Xiaowen Liu,
  • Changsi Jiang,
  • Xue Tang,
  • Yan Luo,
  • Jingshan Gong

摘要

Objective

To evaluate the value of magnetic resonance imaging (MRI) in identifying the pathologic complete response (pCR) of patients with locally advanced rectal cancer (LARC) after neoadjuvant therapy (NAT).

Materials and methods

This retrospective study included 152 patients with LARC who underwent NAT followed by total mesorectal excision (TME) at our hospital between January 2019 and November 2024. The response to NAT was assessed using MRI. At first, the response was assessed according to MRI-based tumor regression grade (mrTRG), which was only on the basis of T2 weighted imaging (T2WI). Then, diffusion weighted imaging (DWI) was added to construct biparametric MRI-based tumor regression grade (BPmrTRG), followed by multiparametric MRI-based tumor regression grade (MPmrTRG) consisting of T2WI, DWI and contrast-enhanced T1-weighted imaging (CE-T1WI). The diagnostic efficacy of the three methods for identifying pCR was assessed by calculating the area under the receiver operating characteristic (ROC) curve (AUC), positive predictive value (PPV), negative predictive value (NPV), sensitivity, and specificity. The DeLong test was used to compare the AUCs of different methods.

Results

Of the 152 patients, 27 (17.8%) were obtained pCR at surgical histopathological analysis. Among the three different MRI-based TRG methods, MPmrTRG archived the highest AUC of 0.891 (95% CI: 0.814–0.957) to identify pCR after NAT, followed by an AUC of 0.840 (95%CI: 0.745–0.916) for BPmrTRG and 0.729 (95% CI: 0.630–0.818) for mrTRG. Paired comparisons showed that AUC of MPmrTRG was higher than that of mrTRG with statistically significant after Bonferroni correction (p = 0.007), as well as the sensitivity (0.815 vs. 0.481, p = 0.008).

Conclusion

After adding DWI and CE-T1WI, the multiparametric MRI approach could improve diagnosis performance for identifying pCR after NAT in patients with LARC, which could facility clinicians’ decision and patients’ consultation for the watch and wait strategy to forgo the surgery and preserve the organ.